For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0506: Idle Speed LowDTC P0507: Idle Speed High
Circuit/System Description
The throttle actuator control (TAC) motor is controlled by the engine control module (ECM). The DC motor located in the throttle body drives the throttle blade. In order to decrease idle speed, along with spark and fuel delivery changes the ECM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the ECM commands the throttle plate open allowing more air to pass the throttle plate.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0443, P0502-if applicable, P0503-if applicable, P1174, P1175, or P2135, is not set. |
| • | The engine is idling for more than 1 second. |
| • | The engine coolant temperature (ECT) is more than -40°C (-40°F). |
| • | The intake air temperature (IAT) is more than -40°C (-40°F). |
| • | The barometric pressure (BARO) is more than 72 kPa. |
| • | The system voltage is between 9-18 volts. |
| • | The vehicle speed is less than 4.8 km/h (3 mph). |
| • | DTC P0506 and P0507 run continuously when the above conditions are met. |
Conditions for Setting the DTC
P0506
| • | The ECM detects that the actual idle speed is approximately 150 RPM lower than the desired idle speed continuously. |
| • | The above condition is present for 3 tests consisting of 8 seconds each test. |
P0507
| • | The ECM detects that the actual idle speed is approximately 150 RPM higher than desired idle speed. |
| • | The above conditions is present for 3 tests consisting of 8 seconds each. |
Action Taken When the DTC Sets
| • | DTC P0506 and P0507 are Type B DTCs. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
Conditions for Clearing the MIL/DTC
DTC P0506 and P0507 are Type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Throttle Actuator Control (TAC) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Using a scan tool compare the desired engine idle speed to the actual engine idle speed.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records list.
| ⇒ | Actual engine idle speed should be no greater than 150 RPM below desired. |
| ⇒ | Actual engine idle speed should be no greater than 150 RPM above desired. |
Circuit/System Testing
- Observe the DTC information on the scan tool.
- Inspect for any condition that can reduce idle speed by increasing engine load.
- Inspect for the following conditions:
| ⇒ | If there are any other DTCs set diagnose those first. |
| • | Incorrect torque converter clutch (TCC) operation |
| • | Accessories that require additional torque to operate |
| • | Excessive deposits in the throttle body |
| • | Restricted exhaust |
| • | Mechanical conditions that limit engine speed |
| ⇒ | Repair any conditions, if necessary. |
| • | Vacuum leaks |
| • | A faulty positive crankcase ventilation (PCV) valve |
Repair Verification
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
